A variety of inflatable sport balls, such as a soccer ball, conventionally exhibit a layered structure that includes a casing, an intermediate layer, and a bladder. The casing forms an exterior portion of the sport ball and is generally formed from a plurality of durable and wear-resistant panels joined together along abutting edges (e.g., with stitching or adhesives). Although panel configurations may vary significantly, the casing of a traditional soccer ball includes thirty-two panels, twelve of which have a pentagonal shape and twenty of which have a hexagonal shape.
The intermediate layer forms a middle portion of the sport ball and is positioned between the casing and the bladder. Among other purposes, the intermediate layer may provide a softened feel to the sport ball, impart energy return, and restrict expansion of the bladder. In some configurations, the intermediate layer or portions of the intermediate layer may be bonded, joined, or otherwise incorporated into the casing as a backing material.
The bladder, which has an inflatable configuration, is located within the intermediate layer to provide an interior portion of the sport ball. In order to facilitate inflation (i.e., with pressurized air), the bladder generally includes a valved opening that extends through each of the intermediate layer and casing, thereby being accessible from an exterior of the sport ball.
In order to facilitate joining of the panels that make up the casing, the casings of many balls are assembled inside-out, thus providing access to flanges at the edges of the panels that typically project inward and are sewn, glued, or welded to flanges of adjacent panels. Once assembly of the inside-out casing is nearly complete, the casing is turned right-side-out, and the final unclosed portions of the casing are joined to complete closure of the casing. For example, in some cases, one or two seams of a casing are left unclosed, providing an opening for the casing to be turned right-side-out through. Once the casing is turned right-side-out, a bladder, restriction layer, and/or other layers may be inserted through the opening before the last seams are joined, providing the final closure of the casing.